In general, I think trying to hide your source from customers is a pointless waste of effort. Anybody with enough bucks and dishonesty to make real (unauthorized) use of your intellectual property probably has more than enough bucks to hire someone to get past your protection scheme, assuming what you have is really that valuable...butesper raises a point I've never thought of: trade secrets.

If you want to protect intellectual property as a trade secret you have to make some explicit efforts to protect that knowledge from outsiders. A sampling of these include NDA's, no-reverse-engineering clauses in software licenses, company policies, headers in your source code files, and so forth. But I can see that distributing code that is easily readable might breach a trade secret, especially if you don't have NDA's in place.

Also, you should clear any encryption/obfustication/blackout technique you use with your lawyer. What counts as sufficient efforts to protect a trade secret depends on case law, varies from country to country, and requires an experienced person to evaluate.

Note: Though I have been involved in the IP process, To be very clear, I am not a lawyer and this is not legal advice - if you are concerned about trade secrets, consult with a lawyer if you haven't already. They can be very tricky to protect and encryption of your source code may not be enough - especially if someone can point to list of nodes and links like Anonymous Monk posted and say: "But he/she should have known that it doesn't *really* protect the source."